Stacked sensors have been proposed in which photoelectrically convertible materials are stacked above semiconductor substrates and which allow a large amount of saturation electric charge even in miniaturized pixels.
FIG. 5 is a cross sectional view of a pixel in a stacked imaging sensor described in Patent Literature (PTL) 1. As shown in FIG. 5, a photoelectric conversion layer 210, a transparent electrode 211, and a pixel electrode 212 are formed above a semiconductor substrate 200. Moreover, plural impurity regions included in output circuits are formed in the semiconductor substrate 200. The impurity region includes an n-type electric charge accumulation part 201 for accumulating electric charges generated in the photoelectric conversion layer 210 and a p-type surface doping region 202 for reducing leakage caused by a surface defect of the semiconductor substrate 200 at the top of the electric charge accumulation part 201. Moreover, in order to output the electric charges accumulated in the charge accumulation part 201 to a signal line, a transfer transistor 204 for transferring the electric charges to a floating diffusion part 203 is formed. The floating diffusion part 203 is connected to a gate of an amplifier transistor 205 in order to convert the electric charges into a voltage according to the amount of the electric charges, and a selection transistor 206 is formed in the floating diffusion part 203 in order to select pixels to be outputted to the signal line. Moreover, a reset transistor 207 is formed to reset electrical potential of the floating diffusion part 203. Moreover, a contact 208 is provided in order to transmit photoelectric charges generated in the photoelectric conversion layer 210 to the electric charge accumulation part 201, and an n-type contact doping region 209 having a high dopant concentration is formed in order to decrease a contact resistance.